1. Field of the Invention
The present invention relates to a vehicle restraint control module having a system for monitoring power interruption and controlling a vehicle system, such as a fuel pump, in the event of a power interruption.
2. Background Art
Current vehicle designs incorporate electronic controls for many functions. Examples of vehicle electronic controls include engine controls, restraint controls, fuel system controls, and the like.
A restraint control module is used to control air bag deployment in the event of a collision. Restraint control modules are powered by the vehicle battery in either the xe2x80x9crunxe2x80x9d or xe2x80x9cstartxe2x80x9d ignition switch positions. Restraint control modules may have backup power supply systems that generally include a capacitor-based backup power supply system. Backup power supply systems for restraint control modules generally have sufficient capacity to power air bag deployment and also to provide control circuit and memory protection.
Restraint control modules constantly monitor data received from sensors, such as accelerometers, radar sensors, ultrasonic sensors and the like that can provide data to the microprocessor that assist in identifying crash severity and are useful in developing safing procedures. Upon receiving data from sensors that is potentially indicative of a collision event, the restraint control module compares the data being received to stored collision data profiles to determine whether a collision has occurred. Upon receiving collision data corresponding to a collision of a predetermined magnitude, the restraint control module may be programmed to shut down other systems such as the fuel pump of the vehicle by interrupting power to the fuel pump.
Currently, a separate electromechanical fuel flow cutoff switch from the restraint control module functions to stop operation of the fuel pump upon sensing an impact. The fuel flow cutoff switch is intended to prevent fuel leakage by disabling the fuel pump. Fuel flow cutoff switches are generally located in the rear portion of a vehicle. Problems may be encountered relating to finding an acceptable location to mount the fuel flow cutoff switch. Another disadvantage of the electromechanical fuel cutoff switch is that it adds cost to the vehicle.
A manual reset button is provided on the vehicle to permit the fuel pump to be reset by a user or service technician after it is determined that it is safe to allow the fuel pump to be operated. The manual reset system requires that the reset button first be located. Information regarding the operation and location of the reset button is generally provided in a vehicle owners manual but many owners are not familiar with the reset procedure. On occasion after a minor collision that triggers the fuel flow cutoff, the vehicle may be safe to drive but is immobilized by the fuel flow cutoff switch. If the owner is unaware of the reset procedure, an unnecessary service call may be required to reset the fuel pump.
It has been proposed that the restraint control module may be used to provide a fuel cutoff switch that is controlled based upon data received from sensor inputs. One drawback of this approach is that the restraint control module cannot distinguish between a normal shutdown that occurs when the key is turned off in the ignition and a short duration power interruption that could conceivably occur during a collision event. Also, it is possible that a brief short circuit could be interpreted by the restraint control module as a power interruption. When power is supplied after a brief interruption, the restraint control module may be reset without storing data acquired during the collision event. While this would not create a problem for restraint control modules that are used solely for air bag deployment, automatic resetting may be unacceptable if the restraint control module is used to control other systems such as the fuel pump to provide a fuel cutoff mechanism.
There is a need for a restraint control module that provides a simple and effective system for cutting off power to the fuel pump when a collision event occurs that will not be automatically reset after a short duration power interruption. There is also a need for a fuel cutoff system that utilizes existing sensors and microprocessor capacity that does not require the use of a manual reset button or separate electromechanical fuel flow cutoff switch. There is also a need for a restraint control module that is effective to store data from sensors acquired during a collision event that is not reset if a power interruption occurs during the collision event.
These and other problems and needs are addressed by applicants"" invention as summarized below.
According to the invention, a method of discriminating between a normal power interruption to a restraint control module and a collision induced power interruption to the restraint control module is provided. According to the method, a digital input bit is set in a microprocessor in a first state when a normal power interruption occurs. The microprocessor monitors for a power interruption to the restraint control module while the restraint control module is powered. The restraint control module monitors sensor output data based upon an algorithm programmed into the microprocessor to determine whether a collision event has occurred. Upon determination that a power interruption has occurred, the algorithm is checked to determine whether the power interruption occurred during a collision event. If so, the digital input bit is set to a second state to indicate that the power interruption occurred during a collision event. With the bit set to its second state, the restraint control module may prevent powering up of a system of the vehicle controlled by the microprocessor.
According to another aspect of the invent on, the system that is prevented from powering up may be the fuel pump of the vehicle. The invention could also be used in conjunction with electric vehicles to prevent powering up of specified components of the electric vehicle if power is interrupted during a collision event.
According to the invention, the sensors may be accelerometers that provide acceleration/deceleration data to the microprocessor. Alternatively, other sensors may be used including radar sensors, ultrasonic sensors and the like.
According to yet another aspect of the invention, the restraint control module may be used to control at least one air bag system.
According to another aspect of the method of the present invention, the microprocessor algorithm includes collision profile data that is stored in memory and compared to the sensor output data to determine if a collision event has occurred.
According to another aspect of the invention, a combined restraint control and fuel system cutoff control module is provided for a vehicle. The restraint control module is connected to a power supply when an ignition switch of the vehicle is in its on position or in its start position. The restraint control module has a microprocessor that is programmed with an algorithm that is used to detect a collision event. At least one sensor provides acceleration/deceleration data to the microprocessor. The microprocessor controls deployment of restraints such as air bags and also controls the fuel system cutoff based upon analysis by the algorithm of the acceleration/deceleration data received by the microprocessor. The microprocessor monitors whether connection of the restraint control module to the power supply has been interrupted and, if so, the microprocessor further determines whether the interruption occurred during a collision event. If it is determined that the interruption occurred during a collision event, the microprocessor enables the fuel system cutoff until the ignition switch is manipulated by an operator to reset the fuel system cutoff.
The combined restraint control and fuel system cutoff control module algorithm utilizes accelerometer output profiles to which acceleration/deceleration data from the sensor is compared to detect a collision event. Other sensors may be used in a similar manner including radar systems, ultrasonic sensors and the like.
According to another aspect of the invention, a short duration power interruption occurring during a collision event may be detected causing the fuel system to be cut off, thereby preventing operation of the fuel system until the ignition is normally turned off and then to its on or start position.
According to another aspect of the invention, the at least one sensor may comprise a plurality of accelerometers or other sensors including radar sensors, ultrasonic sensors and the like.
According to another aspect of the invention, the combined restraint control and fuel system cutoff control module microprocessor is linked to a memory storage apparatus. The memory storage apparatus stores acceleration/deceleration data when a collision event occurs for subsequent analysis until the ignition is cycled off and on.
According to yet another aspect of the invention, the combined restraint control and fuel system cutoff control module preferably includes a backup power supply for powering the restraint control and memory storage apparatus. The backup power supply is enabled only when the power supply is interrupted.
These and other aspects and advantages of the invention will be better understood upon review of the attached drawings in light of the following detailed description.